A compressed air energy storage reservoir cyclic alternating injection-production reservoir evaluation experimental device
Patent Information
- Application Number
- CN202521811934.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-25
- Publication Date
- 2026-10-30
- Estimated Expiration
- 2035-08-25
AI Technical Summary
然而，储能库在实际运行中呈现“大吞大吐、注采交替、高压运行”的特点，单井日注采频次高达1次(远高于传统储气库的1–2次/年)，导致储层承受高频次交变应力
[0017]结合上述的技术方案和解决的技术问题，本实用新型所要保护的技术方案所具备的优点及积极效果为：
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Figure CN224921648U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of compressed air energy storage technology, and in particular relates to an experimental device for evaluating cyclic alternating injection and production reservoirs in compressed air energy storage. Background Technology
[0002] Background Technology: Development and Challenges of Compressed Air Energy Storage (CAES)
[0003] In the context of carbon neutrality, compressed air energy storage, as a core technology for large-scale, long-term physical energy storage, has become a key facility supporting the consumption of renewable energy due to its environmental friendliness (no fossil fuel consumption, zero harmful emissions) and grid peak-shaving capabilities. Underground spaces such as salt caverns and depleted oil and gas reservoirs, due to their enormous storage capacity and geological enclosure, are widely being converted into energy storage facilities to achieve peak shaving and valley filling of electricity. However, in actual operation, these energy storage facilities exhibit characteristics of "large-scale injection and release, alternating injection and production, and high-pressure operation," with a single well's daily injection and production frequency reaching as high as once (far exceeding the 1-2 times / year of traditional gas storage facilities), resulting in the reservoir being subjected to high-frequency alternating stress. This operating condition leads to a core problem: irreversible damage to reservoir permeability. The pore pressure fluctuations caused by multiple rounds of injection and production exacerbate the stress sensitivity effect of the rock skeleton, and permeability decreases exponentially with increasing effective stress. Experiments show that permeability decreases most significantly during the initial pressurization stage (a decrease of 8%-12%), and only partially recovers after depressurization. Long-term cumulative damage will severely weaken the energy storage facility's production capacity. Traditional seepage models do not consider non-Darcy flow and dynamic permeability decay under high-frequency alternation, resulting in a lack of theoretical support for injection-production pressure differential design.
[0004] Background Technology: Limitations of Reservoir Evaluation Experimental Apparatus
[0005] Existing reservoir permeability testing devices are mainly designed for static or single-cycle conditions, which are difficult to simulate actual high-frequency alternating injection and production conditions. They have the following drawbacks: First, the experimental simulation capability is insufficient: the circulation mechanism is simple, and conventional devices only support single pressurization / depressurization tests, which cannot reproduce the high-frequency injection and production stress path of the energy storage reservoir; Second, the confining pressure control accuracy is low: traditional confining pressure pumps have a slow response and are difficult to maintain constant external pressure (simulating the stress of the overlying strata) to achieve dynamic alternation of internal pressure.
[0006] In summary, current reservoir evaluation devices cannot meet the core requirements of high-frequency alternating pressure and high-pressure constant containment pressure, making it difficult for experimental data to guide the optimization of injection and production parameters (such as the maximum / minimum injection-production pressure difference boundary and permeability decay threshold). There is an urgent need for a dynamic experimental device that directly correlates "net effective cover pressure – permeability" to provide a theoretical basis for the safe operation of energy storage facilities.
[0007] Based on the above analysis, the problems and shortcomings of the existing technology are as follows:
[0008] (1) Irreversible damage to reservoir permeability: Fluctuations in pore pressure caused by multiple injection and production cycles exacerbate the stress sensitivity effect of the rock skeleton, and permeability decreases exponentially with increasing effective stress. Experiments show that permeability decreases most significantly during the initial pressurization stage (with a decrease of 8%–12%), and only partially recovers after depressurization. Long-term cumulative damage will severely weaken the reservoir's production capacity. Traditional seepage models do not consider non-Darcy flow under high-frequency alternation and dynamic permeability decay, resulting in a lack of theoretical support for the injection-production pressure difference design.
[0009] (2) Existing reservoir permeability testing devices are mainly designed for static or single-cycle conditions, which are difficult to simulate actual high-frequency alternating injection and production conditions. They have the following defects: First, the experimental simulation capability is insufficient: the cycle mechanism is simple, and conventional devices only support single pressurization / depressurization tests, which cannot reproduce the high-frequency injection and production stress path of the energy storage reservoir; Second, the confining pressure control accuracy is low: the traditional confining pressure pump has a slow response and it is difficult to maintain constant external pressure (simulating the stress of the overlying strata) to achieve dynamic alternation of internal pressure. Summary of the Invention
[0010] To address the problems existing in the prior art, this utility model provides an experimental device for evaluating cyclic alternating injection and production reservoirs in a compressed air energy storage system.
[0011] This invention is achieved as follows: A cyclic alternating injection-production reservoir evaluation experimental device for compressed air energy storage includes:
[0012] Gas cylinders, pressure regulating valves, pressure gauges, core holders, soap film flow meters, and hand pumps;
[0013] The right end of the gas cylinder is connected to a pressure regulating valve via an air pipe; the right end of the pressure regulating valve is connected to a pressure gauge via an air pipe; the bottom of the pressure gauge is connected to a core holder via an air pipe; the right end of the core holder is connected to the pressure gauge via an air pipe.
[0014] Furthermore, the bottom of the pressure gauge is connected to a soap film flow meter via an air tube.
[0015] Furthermore, the right end of the soap film flow meter is connected to a hand-cranked pump via an air pipe.
[0016] Furthermore, the core holder: seals and fixes the core, and has a built-in confining pressure cavity (connected to a hand-cranked pump).
[0017] Based on the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solution to be protected by this utility model are as follows:
[0018] First, this utility model, through device structure optimization and experimental path design, constructs an experimental system with both alternating pressure and dynamic monitoring capabilities, which can realistically simulate the complex stress environment caused by high-frequency injection and production in compressed air energy storage. During the device development process, key technical indicators such as confining pressure control stability, core clamping sealing, and flow detection accuracy were repeatedly tested and verified, ultimately achieving a highly realistic and adaptable experimental platform. Application tests of this device under multiple rounds of alternating loading verified its experimental feasibility, data continuity, and dynamic permeability decay monitoring capabilities. This demonstrates that the technical solution not only effectively solves the technical problems of traditional equipment's inability to simulate alternating injection and production stress paths and data discrepancies, but also provides directly applicable theoretical support and quantitative basis for subsequent optimization of energy storage safety operation parameters, possessing significant technical innovation and engineering application value. The specific description is as follows:
[0019] 1. Realistic Working Condition Simulation: Breaking through the limitations of traditional static experiments that only use fixed confining pressure, this method flexibly adjusts the confining pressure using a hand-cranked pump to reproduce the cyclic alternating stress of "gas injection and pressurization - gas production and depressurization" during the gas storage injection and production process. This ensures that the mechanical environment of the core is highly consistent with the dynamic pressure changes of the underground reservoir, reducing the deviation between static experiments and actual field conditions. This provides a realistic scenario to support subsequent research on seepage patterns and ensures that experimental data can directly reflect the real response of the reservoir under dynamic injection and production.
[0020] 2. Scientific and Quantitative Methodology: The process integrates confining pressure control, seepage testing, and permeability calculation, achieving seamless data linkage across the entire process. Confining pressure control is matched to stress changes during the injection and production stages, simultaneously monitoring data such as seepage velocity and pressure loss. Then, permeability values are derived using standardized formulas, quantitatively revealing the correlation between "confining pressure change and permeability fluctuation." This provides directly applicable quantitative data for optimizing the injection-production pressure difference in gas storage facilities and assessing long-term stability, solving the problem of data fragmentation inherent in traditional methods.
[0021] 3. High versatility: The simplified structural design and modular clamping system are compatible with cores of different sizes and lithologies (sandstone, carbonate rocks, etc.) without the need for frequent replacement of core components. It can compare differences between different cores and track dynamic changes within the same core, reducing experimental errors.
[0022] 4. Balancing Safety and Visualization: The system is equipped with dual pressure gauges and a soap film flow meter, enabling real-time monitoring of pressure and gas seepage velocity at both ends of the core sample, thus avoiding the risk of overpressure. The soap film flow meter features an intuitive and visual structure, allowing direct observation of gas velocity changes during the experiment; the core holder has strong sealing properties and leak-proof functionality, ensuring a safe and stable testing process.
[0023] Secondly, this invention can highly replicate the mechanical conditions of high-frequency alternating injection and production in a compressed air energy storage facility under laboratory conditions, achieving multi-cycle internal pressure regulation under constant confining pressure and simultaneously measuring the dynamic changes in permeability. This technical solution offers the following value:
[0024] 1. Enhanced safety, extended lifespan, and reduced costs: By realistically simulating the dynamic stress experienced by underground reservoirs during injection and production, the quantitative relationship between confining pressure changes and permeability decay is obtained, providing a basis for determining the maximum and minimum injection-production pressure difference, reducing the risk of irreversible permeability damage, and avoiding early reservoir failure; by optimizing the injection-production system using experimental data, the permeability decay process can be effectively delayed, reducing repair or abandonment caused by reservoir damage, and lowering long-term operation and maintenance costs.
[0025] 2. Wide range of application value: The device has a simple structure and a high degree of modularity, and is suitable for various rock types (such as sandstone and carbonate rocks) and cores of different sizes. It is not only suitable for compressed air energy storage, but can also be extended to underground engineering fields involving multiple injection and production, such as carbon dioxide geological storage.
[0026] 3. Dual economic and social value: This device can promote the efficient consumption of renewable energy and improve the grid's peak-shaving capacity, thus having significant economic and social benefits.
[0027] Currently, there is no dedicated experimental device, either domestically or internationally, for the dynamic evaluation of reservoir permeability under cyclic injection and production conditions in compressed air energy storage. Existing equipment is mostly limited to static or single-cycle testing, failing to meet the experimental requirements of multiple rounds of internal pressure alternation. This invention breaks through the limitations of experimental boundaries for the first time: expanding from static / single-cycle testing to high-frequency, multi-cycle testing; and overcomes the limitation of insufficient stress control capabilities: achieving constant confining pressure while flexibly adjusting internal pressure, accurately reproducing the on-site gas injection pressurization and gas production depressurization paths.
[0028] The cumulative irreversible damage to reservoir permeability caused by the "daily injection and extraction, alternating high pressure" operating conditions in actual energy storage facilities is a long-standing technical challenge that has been difficult to accurately reproduce and quantify in the laboratory. The main difficulties include: the inability to stably simulate multiple rounds of dynamic stress under constant confining pressure in the laboratory; the lack of experimental data to support the variation of permeability under high-frequency alternating injection and extraction; and the fragmentation of experimental data, making it difficult to establish a quantitative correlation between confining pressure and permeability.
[0029] This invention utilizes a pressure control system consisting of a confining pressure chamber and a hand-cranked pump, along with a soap film flow meter and dual pressure gauges, to achieve controllable simulation of coordinated changes in internal and external pressure. Furthermore, it continuously acquires permeability change curves under multiple rounds of pressure increases and decreases in a single experiment, providing directly applicable experimental data for optimizing energy storage operation parameters.
[0030] For a long time, the industry has generally believed that reservoir permeability evaluation can be carried out under static or low-frequency cycling conditions, ignoring the cumulative impact of high-frequency alternating stress on permeability. This technical bias leads to: significant differences between test results and actual operating conditions, making it impossible to accurately predict reservoir performance degradation under long-term operation; and a lack of quantitative consideration of high-frequency alternating damage in injection-production pressure differential design, resulting in operational risks.
[0031] This invention proactively introduces multiple rounds of high-frequency alternating internal pressure paths in the experimental design while maintaining constant confining pressure, ensuring that the experimental conditions closely match actual field conditions. Experimental results show that permeability decreases most significantly during the early stress-increase phase, recovering only partially after depressurization. This verifies the existence of irreversible attenuation under high-frequency alternating conditions, thus overcoming the limitations of traditional experimental techniques and correcting long-standing engineering design deviations. Attached Figure Description
[0032] Figure 1 This is a structural diagram of the experimental device for evaluating the cyclic alternating injection and production reservoir of compressed air energy storage provided in this embodiment of the utility model.
[0033] Figure 1 The components are: 1. Gas cylinder, 2. Pressure regulating valve, 3. Pressure gauge A, 4. Core holder, 5. Pressure gauge B, 6. Soap film flow meter, 7. Hand pump.
[0034] Figure 2 This is a graph showing the change of K / K0 in core sample No. 1 as a function of net effective overburden pressure, provided in this embodiment of the present invention.
[0035] Figure 3 This is a graph showing the change of K / K0 in core sample No. 2 as a function of net effective cover pressure, provided in this embodiment of the present invention. Detailed Implementation
[0036] To make the objectives, technical solutions, and advantages of this utility model clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this utility model.
[0037] like Figure 1 As shown in the figure, the experimental device for evaluating a cyclic alternating injection-production reservoir in a compressed air energy storage system provided in this embodiment of the present invention includes:
[0038] 1. Gas cylinder; 2. Pressure regulating valve; 3. Pressure gauge; 4. Core holder; 5. Pressure gauge; 6. Soap film flow meter; 7. Hand pump.
[0039] The right end of gas cylinder 1 is connected to pressure regulating valve 2 via an air pipe; the right end of pressure regulating valve 2 is connected to pressure gauge 3 via an air pipe; the bottom of pressure gauge 3 is connected to core holder 4 via an air pipe; the right end of core holder 4 is connected to pressure gauge 5 via an air pipe.
[0040] The pressure gauge 5 provided in this embodiment of the utility model is connected to the soap film flow meter 6 at the bottom via an air pipe.
[0041] The soap film flow meter 6 provided in this embodiment of the utility model is connected to a hand-cranked pump 7 via an air pipe on its right end.
[0042] The core holder 4 provided in this embodiment of the utility model: seals and fixes the core, and has a built-in confining pressure cavity (connected to a hand-cranked pump 7).
[0043] Cylinder 1: Simulates the gas injection source, providing stable and controllable compressed air;
[0044] Pressure regulating valve 2: controls the gas flow and stops the gas injection process;
[0045] Pressure gauge 3: Real-time measurement of the pressure P1 at the core inlet;
[0046] Core holder 4: Seals and fixes the core, with an internal confining pressure cavity (connected to hand pump 7) to simulate formation stress;
[0047] Pressure gauge 5: measures the pressure P2 at the core outlet in real time, and has the same specifications as pressure gauge 3;
[0048] Soap film flow meter 6: The soap film flow meter measures the flow rate of seepage gas in the rock core;
[0049] Hand-cranked pump 7: applies confining pressure to the core holder to simulate cyclic alternating injection and production, supporting alternating adjustment.
[0050] The experimental setup employs a combination of a series-connected gas passage and a confining pressure simulation mechanism. Gas cylinder 1, located at the leftmost end of the system, provides compressed air. It is connected to pressure regulating valve 2 via a gas pipe. Valve 2 controls the opening and closing of the gas source and regulates the pressure, ensuring a stable and controllable flow and pressure of the gas entering the system. The outlet of valve 2 is connected to pressure gauge 3, which is fixed at the gas pipe node. Pressure gauge 3 monitors the inlet pressure P1 before it enters the core holder 4 in real time, thus ensuring the controllability of the gas injection conditions.
[0051] A core holder 4 is positioned at the core of the gas injection path, with its two ends connected to pressure gauges 3 and 5, respectively. The core holder 4 is used to seal and fix the core sample. It contains a confining pressure chamber, which, through connection to a hand-operated pump 7, applies controllable confining pressure to simulate the stress conditions of the underground formation environment. The design of the core holder 4 ensures that during the gas seepage experiment, it maintains both the axial gas passage and achieves cyclical stress through lateral confining pressure, thus realistically reflecting the working state of the underground reservoir.
[0052] A pressure gauge 5, identical in specification to pressure gauge 3, is connected to the outlet end of the core holder 4. It is used to measure the pressure P2 at the core outlet in real time, forming an inlet-outlet pressure difference monitoring system. By comparing the values of P1 and P2, the pressure loss characteristics during core permeation can be directly reflected, providing fundamental data for evaluating permeability and dynamic response. Below pressure gauge 5, a soap film flow meter 6 is connected via a gas tube. The soap film flow meter 6 uses a soap film-driven method to measure flow rate, accurately measuring the gas permeation flow rate after passing through the core, which is a crucial testing step for evaluating core permeability performance.
[0053] The outlet of the soap film flowmeter 6 is connected to the hand-cranked pump 7, forming a closed loop. The hand-cranked pump 7 maintains the gas flow loop through its connection to the flowmeter, and also communicates with the confining pressure chamber of the core holder 4 via a separate connecting pipe, enabling the application and alternating adjustment of the confining pressure. The hand-cranked pump 7 can be manually adjusted to change the confining pressure at different stages, simulating the pressure fluctuations during the injection and production cycles of a compressed air energy storage system, thus making the experimental conditions closer to the real formation environment.
[0054] In terms of overall working principle, gas cylinder 1 provides stable compressed air, pressure regulating valve 2 realizes start / stop and pressure control, pressure gauges 3 and 5 record the pressure difference before and after the core sample, core holder 4 fixes the sample and maintains the seepage path under confining pressure, soap film flow meter 6 measures the seepage gas flow rate, and hand-cranked pump 7 simulates the cyclical alternation of confining pressure. This structure enables accurate simulation of the changes in reservoir stress and seepage characteristics during the injection and production cycles of a compressed air energy storage system under laboratory conditions, providing reliable experimental evidence for reservoir evaluation and optimization.
[0055] The specific operating steps of the experimental setup are as follows:
[0056] The core to be tested is placed in the core holder 4, and then... Figure 1 Connecting pipelines.
[0057] Ensure that the gas source 1 has sufficient pressure and that the pipeline is leak-free; that the clamp seal is intact to prevent core leakage; that the soap film flow meter 6 has sufficient soap solution and that the pipeline is unobstructed; and that the hand pump 7 is functioning properly and can stably provide confining pressure. Ready to begin the experiment.
[0058] The hand-cranked pump 7 is set with an initial confining pressure σ0 to simulate the original stress of the formation. Control valve 2 is opened, and data is recorded after P1, P2, and Q stabilize synchronously.
[0059] The hand-cranked pump 7 adjusts the confining pressure using the "increase-decrease-circulation" function. During the experiment, temperature, pressure, and flow rate data are recorded at regular intervals (customizable). To avoid experimental errors, 3-5 sets of pressure values are typically selected for testing.
[0060] The penetration rate was obtained by processing the data using a modified Darcy's Law formula:
[0061]
[0062] Further data analysis will be conducted.
[0063] Through twelve sets of variable internal pressure and constant external pressure (six cycles, with one cycle consisting of an increase and a decrease), the relationship between the relative change of permeability and the net effective overburden pressure in the core under high production pressure differential stress-sensitive test of "six increases and six decreases" was explored.
[0064] To verify the application effect of the "compressed air energy storage cyclic alternating injection and production reservoir evaluation experimental device" proposed in this utility model in the dynamic testing of reservoir core permeability, a typical "six-rise and six-fall" confining pressure alternating loading experiment was carried out to simulate the influence of high-frequency injection and production process on permeability.
[0065] 1. Experimental parameter settings:
[0066] Core dimensions: Core No. 1: Length L = 5.836 cm, Diameter D = 2.498 cm; Core No. 2: Length L = 5.158 cm, Diameter D = 2.500 cm
[0067] Experimental gas: Nitrogen (viscosity μ = 0.017812 mPa·s);
[0068] Confining pressure path: 28.5MPa→32.5MPa→36.5MPa→40.5MPa→44.5MPa→48.5MPa→52.5MPa→48.5MPa→44.5MPa→40.5MPa→36.5MPa→32.5MPa→28.5MPa (simulating one injection-production cycle). Complete six cycles according to the above experimental steps.
[0069] Internal pressure regulation method: The pressure regulating valve provides precise control to maintain stable airflow at each stage;
[0070] Experimental temperature: room temperature (approximately 25°C);
[0071] Flow measurement: P1, P2 and flow velocity data were obtained using a soap film flow meter and dual differential pressure monitoring method;
[0072] 2. Experimental phenomena and results:
[0073] The permeability decreased most significantly after the first pressurization, and then decreased with each subsequent cycle. During the depressurization process, permeability partially recovered, but remained below its initial value, indicating irreversible damage. After the sixth cycle, the permeability tended to stabilize, suggesting that the reservoir's seepage capacity tended to saturate after being pressurized to a certain stage.
[0074] The plotted "net effective confining pressure – permeability" curve exhibits a clear nonlinear stress-sensitive characteristic (e.g., Figure 2, Figure 3 ).
[0075] 3. Project Applicability Analysis:
[0076] This experimental setup can be used in the early stages of engineering to screen suitable injection-production boundaries for reservoirs and to identify vulnerable core samples in advance.
[0077] During the design phase, it can be used to assess the degree of core damage under different injection and production regimes and to optimize the circulation frequency and pressure differential.
[0078] In scientific research and teaching settings, this device can be used to demonstrate the impact of injection-production alternation on the micro-seepage mechanism of cores, and has dual value for teaching and scientific research.
[0079] The experimental results can be directly input into the seepage simulation model to improve the accuracy and predictive ability of geological simulation.
[0080] Based on the experimental results of the device under the conditions of "real core – alternating path – quantitative output", it is proven that the technical solution is not only feasible but also highly innovative. It can be promoted and applied in fields such as compressed air energy storage, gas storage design, and underground fluid engineering, and has significant technical practical value and engineering guidance significance.
[0081] like Figure 2 , Figure 3 As shown, the core permeability gradually decreased with the increase of production pressure differential during the six pressure increases and decreases; and the decrease in permeability was relatively large in the early stage of the increase in effective stress, while the decrease was relatively small in the later stage; when the effective stress increased to a certain extent, the permeability tended to remain constant.
[0082] After the core is depressurized, the permeability recovers to a certain extent but cannot return to its original value, meaning that the permeability undergoes a partially irreversible change. The rock permeability decreases after each pressure increase or decrease, so the maximum and minimum injection-production pressure difference during the production process can be determined based on the trend of permeability changes.
[0083] The above description is only a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any modifications, equivalent substitutions and improvements made by those skilled in the art within the technical scope disclosed in this utility model, and within the spirit and principles of this utility model, should be included within the protection scope of this utility model.
Claims
1. An experimental device for evaluating cyclic alternating injection-production reservoirs in a compressed air energy storage system, characterized in that, The device includes a gas cylinder, a pressure regulating valve, a first pressure gauge, a core holder, a second pressure gauge, and a soap film flow meter, all connected sequentially via a gas pipe. The soap film flow meter is connected to a hand-cranked pump via the gas pipe. The core holder has an inlet and an outlet; the inlet is connected to the first pressure gauge, and the outlet is connected to the second pressure gauge. The core holder includes a sealed cavity, a confining pressure cavity, and an axial channel penetrating both ends of the sealed cavity. The confining pressure cavity is connected to the hand-cranked pump via a pipeline. The confining pressure cavity is formed by a metal sleeve and a sealing ring, creating a sealed space. The outer wall of the sealed cavity has an interface for connecting pipelines.
2. The experimental apparatus according to claim 1, characterized in that, The pressure regulating valve is installed on the gas pipe between the gas cylinder and the first pressure gauge, and is used to regulate the gas pressure entering the core holder.
3. The experimental apparatus according to claim 1, characterized in that, The first and second pressure gauges have the same structure and are installed on the inlet and outlet pipes of the core holder, respectively.
4. The experimental apparatus according to claim 1, characterized in that, The soap film flow meter is installed on the outlet pipeline between the second pressure gauge and the hand pump, and the outlet end of the soap film flow meter is connected to the hand pump through an air pipe.